1. Field of the Invention
The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for mitigating uplink interference in the wireless communication system.
2. Discussion of the Related Art
Based on a proposed standard of IEEE (Institute of Electrical and Electronics Engineers) 802.16, BWA (Broadband Wireless Access) supporting OFDMA (Orthogonal Frequency Division Multiplexing Access) allows to transmit much information in a short time owing to a broadband frequency, wherein the frequency in one frequency band is divided and is then efficiently used by plural users.
This wireless communication system one-dimensionally allocates data bursts for an uplink duration except a predetermined region in a symbol (time)-first order. That is, if the data burst allocation is completed for all subchannels in a certain symbol, the data burst allocation is started for the subchannels in the next symbols. This method implies that all the subchannels for each sector are used for the data burst allocation.
However, as shown in FIG. 1, if the data burst is allocated to all the subchannels in each sector for the uplink duration, interference may occur by the neighboring sectors. In order to overcome this problem, if a cell loading factor is equal to or greater than a predetermined value, as shown in FIG. 2, the data burst is allocated to all the subchannels for each sector, and a permbase value for permutation of the sector is differently set for each sector. Accordingly, the inter-sector interference is averaged out for each subchannel, and thus the interference of the neighboring sectors is mitigated. If the cell loading factor is less than the predetermined value, as shown in FIG. 3, a method has been proposed for mitigating the interference among the sectors by differently setting a subchannel region to be allocated with the data burst for each sector, and setting the same permbase value in each sector for permutation.
For mitigating the interference for the uplink duration by the aforementioned method, it is required to dynamically change the aforementioned set information to define the data burst allocation region according to the cell loading status.
However, the aforementioned set information may be formed with TLV (Type, Length, Value) such as UL allocated subchannels bitmap or UL AMC allocated physical bands bitmap. However, the aforementioned TLV is included in UCD (Uplink Change Descriptor). That is, if the aforementioned set information is changed, considerable time is needed until the changed set information is applied to each mobile station. Eventually, it is difficult to efficiently mitigate the sector interference for the uplink duration.